All MayaMan attributes are regular MEL attributes, and can thus be scripted just like Maya attributes.
These commands exist to help move data between MayaMan's internals, and external MEL scripts. As these are largely used internally, we won't document them fully here.
If you feel you need more scripting control over MayaMan, refer to the included MEL scripts that use these commands, or type 'help MayaManInfo' and 'help MayaManSetData' in the Maya script editor (with the MayaMan plugin loaded of course)